Time division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern. The time domain is divided into several recurrent time slots of fixed length, one for each subchannel. A sample byte or data block of first subchannel is transmitted during a first time slot, a second subchannel is transmitted during a second time slot, and so forth.